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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

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#ifndef SHARE_PRIMS_METHODCOMPARATOR_HPP

#define SHARE_PRIMS_METHODCOMPARATOR_HPP

#include "interpreter/bytecodeStream.hpp"

#include "oops/constantPool.hpp"

#include "oops/method.hpp"

// methodComparator provides an interface for determining if methods of

// different versions of classes are equivalent or switchable

class MethodComparator {

 private:

  static BytecodeStream *_s_old, *_s_new;

  static ConstantPool* _old_cp;

  static ConstantPool* _new_cp;

  static bool args_same(Bytecodes::Code c_old, Bytecodes::Code c_new);

  static bool pool_constants_same(int cpi_old, int cpi_new);

  static int check_stack_and_locals_size(Method* old_method, Method* new_method);

 public:

  // Check if the new method is equivalent to the old one modulo constant pool (EMCP).

  // Intuitive definition: two versions of the same method are EMCP, if they don't differ

  // on the source code level. Practically, we check whether the only difference between

  // method versions is some constantpool indices embedded into the bytecodes, and whether

  // these indices eventually point to the same constants for both method versions.

  static bool methods_EMCP(Method* old_method, Method* new_method);

};

#endif // SHARE_PRIMS_METHODCOMPARATOR_HPP